Page 77 - ITPS-8-2

INNOSC Theranostics and
Pharmacological Sciences Ketamine and SOD activity in schizophrenia

2.4.3. EPM One unit of SOD activity is defined as the amount of

Cognitive function was assessed using an EPM apparatus SOD necessary to cause 50% inhibition of the oxidation of
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with 2 open arms (25 × 5 cm) and 2 closed arms (25 × 5 adrenaline.
× 20 cm) extending from the cross-center platform (5 × 2.6. Statistical analysis
5 cm). The entire apparatus was elevated to 50 cm above
the floor. At the start of the test, each mouse was placed on The data (behavioral and biochemical) were expressed
the cross-center platform facing an open arm. The latency as mean ± S.E.M and analyzed using one-way analysis
period to enter the open arms was observed and recorded of variance and post hoc tests (Student’s Newman-Keuls)
for 5 min using a stopwatch as a paradigm for assessing for the multiple comparisons where appropriate using
®
memory impairment. 13,27 A prolonged delay in entering GraphPad InStat Biostatistics software (GraphPad
the open arms was considered an indicator of altered Software Inc. USA). A level of P < 0.05 was considered
exploratory performance, representing anxiety-induced statistically significant for all tests.
decision-making deficits in working memory. Before 3. Results
testing, each mouse was exposed to the EPM apparatus for
5 min daily over 3 consecutive days to ensure familiarity. 3.1. KET-induced hyperactivity

2.5. Biochemical analysis Locomotor activity, assessed by measuring movement counts
over 5 min (in seconds) and the number of rearing events,
Immediately after the behavioral tests, each mouse was showed that the KET group exhibited a significant (P < 0.05)
sacrificed by cervical dislocation, performed by trained increase in movement counts and rearing events in the OFT
and experienced personnel, in accordance with the compared to the VEH and KET + RISP groups. Specifically,
institution and national guidelines on animal welfare. the KET group showed an average movement of 549.0 ± 19.9
Then, the animals were decapitated, and their brain and 16.40 ± 0.93 rearing events. The control group (VEH)
tissues were carefully removed. The whole brain tissue showed an average movement of 377.4 ± 14.6 and 9 ± 0.71
of each animal was homogenized for 60 s in 5 mL of rearing events, while the RISP-treated group (KET + RISP)
10% w/v cold phosphate buffer (0.1 M, pH 7.4, 4°C) showed an average movement of 446.0 ± 10.2 and 10.40 ±
using a homogenizer. The homogenates were stored in 0.93 rearing events, respectively (Table 1). The significant
a refrigerator until biochemical analysis was carried increase in both movement counts and rearing events in the
out. Subsequently, the homogenates were centrifuged at KET group suggests that KET induces hyperactivity. The
10,000 g for 10 min at 4°C. The resulting homogenized control group showed the lowest activity levels, while the
supernatant was separated from the pellets for SOD KET + RISP group exhibited intermediate activity (Table 1),
activity assay. The SOD activity in each brain homogenate indicating that RISP may mitigate some of the hyperactive
was determined as described. Briefly, 0.5 mL of behavior induced by KET (20 mg/kg, i.p.) administration.
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the homogenate was diluted with 4.5 mL of distilled
water to make a 1 in 10 dilution. Anhydrous sodium 3.2. Exploratory performance in the EPM
bicarbonate (6.897 g) was added to the carbonate buffer The KET group showed poor exploratory performance
solution to achieve a pH of 10.2. An aliquot of 0.2 mL in the EPM test, with significant increase (P < 0.05) in
of the diluted sample was added to 2.5 mL of 0.05 M latency to enter the open arms. The mean latency value
carbonate buffer (pH 10.2) and allowed to equilibrate for the KET group was 34.30 ± 1.77 s, in contrast to 18.79
in a spectrophotometer. The reaction was initiated by ± 0.47 and 24.36 ± 1.75 s for the VEH and KET + RISP
adding 0.3 mL of freshly prepared 0.3 mM adrenaline groups, respectively (Table 2). The increased latency in the
(epinephrine) dissolved in distilled water, which was KET group suggests that KET impaired spatial memory, as
quickly mixed by inversion. The reference cuvette (blank) evidenced by the poor performance after prior exposure
contained 2.5 mL of carbonate buffer, 0.3 mL of substrate and the increased time spent to enter the open arms. The
(adrenaline), and 0.2 mL of distilled water. The increase control group showed the shortest latency, while the KET
in absorbance at 480 nm was monitored for 60, 120, and + RISP group showed an intermediate latency (Table 2),
180 s. suggesting that RISP may have cognitive-enhancing effect,
A3-A0
Calculation: Increase in absorbance per minute = ; 28 reducing the altered decision-making and exploratory
2.5 performance deficits induced by KET administration.
Where A = absorbance after 60 s, A = absorbance after 180 s
0 3 3.3. KET increases SOD activity
Increaseinabsorbanceforsubstrate Animals in the KET group, which received KET alone
%inhibition=100- × 100
Increaseinaabsorbanceforblank for the duration of the experiment, showed a significant

Volume 8 Issue 2 (2025) 71 doi: 10.36922/itps.6372